Granular epoxy resin, production method thereof, and granular epoxy resin package

ABSTRACT

A granular epoxy resin is made by pulverizing an epoxy resin which is solid at ordinary temperature and can exhibit excellent fluidity during molding because of its low melt viscosity in which the total content of components having a molecular weight of 500 or less among components of n 1 =0 in the following general formula (1) and/or components of n 2 =0 in the following general formula (2) is 50% by mass or more of the entire epoxy resin, or, the total content of components having a molecular weight 400 or less among components of n 1 =0 in the following general formula (1) and/or components of n 2 =0 in the following general formula (2) is 20% by mass or more of the entire epoxy resin. The content of low molecular weight compounds having a molecular weight 200 or less in the granular epoxy resin is 0.3% by mass or less. The granular epoxy resin allows easy handling because it hardly causes blocking during storage and transportation

FIELD OF THE INVENTION

The present invention relates to a granular epoxy resin which canexhibit excellent fluidity during molding because of its low meltviscosity and allows easy handling because it hardly causes blockingduring storage and transportation and a production method thereof andalso relates to a package thereof.

BACKGROUND OF THE INVENTION

Epoxy resins have been used in various industrial fields such asadhesives, casting, encapsulation, lamination, molding, coatings, andinsulation because of their excellent physical properties when cured andthe ease of handling. Epoxy resins are generally categorized into aliquid type of which epoxy resins are liquid at ordinary temperature anda solid type of which epoxy resins are solid at ordinary temperature.Normally, such solid type epoxy resin is accommodated in an envelopetype container in a powder or flaky form during the storage and thetransportation. The solid type epoxy resin easily causes a phenomenoncalled “blocking” during the storage and the transportation due to itslow molecular weight. The blocking is a phenomenon that particles ofepoxy resin fuse and unite. The blocking leads to a serious handlingproblem that it becomes difficult to take out the resin from thecontainer and to put the resin in another container for use.

In current years, in the use application of solid epoxy resins such aspowder coatings or encapsulants for semiconductors, the trend is towarduse of solid epoxy resins having further lower molecular weight for thepurpose of improving the fluidity during molding. Accordingly, theabove-mentioned blocking problem becomes increasingly serious.

Conventionally, the epoxy resin is therefore stored and transported atcool temperature in order to prevent the blocking, but there has been aproblem of making the cost higher (“New Epoxy Resin” p35–p36 written byHiroshi Kakiuchi and issued by Shokodo Co., Ltd. May 30, 1988).

It is an object of the present invention to provide a granular epoxyresin which can exhibit excellent fluidity during molding because of itslow melt viscosity and allows easy handling because it hardly causesblocking during storage and transportation, production method thereof,and a package thereof.

SUMMARY OF THE INVENTION

A granular epoxy resin according to the present invention is a granularmatter of an epoxy resin which is solid at ordinary temperature and ismainly composed of one or more selected from oligomers represented bythe following general formula (1) and oligomers represented by thefollowing general formula (2).

[In the above formula (1), G is a glycidyl group.

R¹ is a hydrocarbon group having from 1 to 10 carbon atoms and each R¹can be the same or different.

X is a divalent hydrocarbon group having from 1 to 18 carbon atoms, —O—,—S—, or a group represented by the following general formula (3) andeach X can be the same or different.

(in the above formula (3), G is a glycidyl group, R³ is a hydrogen atomor a hydrocarbon group having from 1 to 5 carbon atoms.)

p¹ is an integer between 0 and 4 and each p¹ can be the same ordifferent.

n¹ is an integer between 0 and 10.]

[In the above formula (2), R² is a hydrocarbon group having from 1 to 10carbon atoms and each R² can be the same or different.

Y is a divalent hydrocarbon group having from 1 to 18 carbon atoms, —O—,—S—, —CO—, —SO₂—, or a direct bond and each Y can be the same ordifferent.

p² is an integer between 0 and 4 and each p² can be the same ordifferent.

n¹ is an integer between 0 and 10.]

In a first aspect of the invention, at least 50% by mass of the granularepoxy resin consists of at least one oligomer of n¹=0 in theaforementioned general formula (1) and having a molecular weight of 500or less and/or at least one oligomer of n²=0 in the aforementionedgeneral formula (2) and having a molecular weight of 500 or less. Thetotal content of compounds having a molecular weight of 200 or less is0.3% by mass or less of the entire epoxy resin.

In a second aspect of the invention, at least 20% by mass of thegranular epoxy resin consists of at least one oligomer n¹=0 in theaforementioned general formula (1) and having a molecular weight 400 orless and/or at least one oligomer of n²=0 in the aforementioned generalformula (2) and having a molecular weight of 400 or less. The totalcontent of compounds having a molecular weight of 200 or less is 0.3% bymass or less of the entire epoxy resin.

Since the content of low molecular weight fragments is a predeterminedamount or more, the granular epoxy resin of the present inventionexhibits excellent fluidity during molding because of its low meltviscosity. On the other hand, since the content of particular lowmolecular weight compounds which easily cause blocking is apredetermined amount or less, the granular epoxy resin allows easyhandling because it hardly causes blocking during storage andtransportation.

Generally, an epoxy resin is a mixture which is mainly composed ofoligomer(s) having a chemical structure represented by theaforementioned general formula (1) or the aforementioned general formula(2). The number of repeats or polymerization degree(n¹, n²) in thegeneral formula (1) and the general formula (2) is 0 or a positiveinteger. Typical epoxy resin is a mixture of a lot of components havingdifferent numbers of polymerization degree. The form, liquid or solid,of epoxy resin depends on the proportion of the components.

In a solid epoxy resin, the larger the amount of the components of whichnumber of polymerization degree is 0 (components of n¹=0 and n²=0)and/or the lower the molecular weight of the components, the lower themelt viscosity of the epoxy resin is so that the epoxy resin can exhibitexcellent fluidity during molding, but easily causes the blocking.Particularly, a solid epoxy resin in which components having a molecularweight of 500 or less among components of which number of polymerizationdegree is 0 occupy 50% by mass or more, or components having a molecularweight of 400 or less among components of which number of repeats orcycles is 0 occupy 20% by mass or more easily causes the blocking.

On the other hand, typical epoxy resin contains a small amount of waterand a small amount of residuals of organic compounds which was used forthe preparation of the epoxy resin. The compounds having a molecularweight of 200 or less accelerate the occurrence of blocking even with asmall amount because the molecular weights thereof are too low.

The granular epoxy resin of the present invention is designed to hardlycause blocking by setting the content of compound having a molecularweight of 200 or less to a predetermined amount or less in solid epoxyresin containing a large amount of components of which number ofpolymerization degree is 0 as mentioned above.

A production method of granular epoxy resin of the present inventioncomprises: an epoxy resin preparing step of preparing an epoxy resinwhich is solid at ordinary temperature by reaction between a phenolcompound and epihalohydrin; a purifying processing step of refining theprepared epoxy resin which is solid at ordinary temperature so that thetotal content of compounds having a molecular weight of 200 or less is0.28% by mass or less of the entire epoxy resin; and a pulverizing stepof pulverizing the refined epoxy resin obtained by the purifyingprocessing step under conditions so as not to make the total content ofcompounds having a molecular weight of 200 or less exceeding 0.3% bymass.

In one aspect of the production method, the epoxy resin which is solidat ordinary temperature prepared by the epoxy resin preparing step ismainly composed of at least one selected from oligomers represented bythe aforementioned general formula (1) and oligomers represented by theaforementioned general formula (2). At least 50% by mass of the entireepoxy resin consists of at least one oligomer of n¹=0 in theaforementioned general formula (1) and having a molecular weight of 500or less and at least one oligomer of n²=0 in the aforementioned generalformula (2) and having a molecular weight of 500 or less.

In the other aspect of the production method, the epoxy resin which issolid at ordinary temperature prepared by the epoxy resin preparing stepis mainly composed of at least one selected from oligomers representedby the aforementioned general formula (1) and oligomers represented bythe aforementioned general formula (2). At least 20% by mass of theentire epoxy resin consists of at least one oligomer of n¹=0 in theaforementioned general formula (1) and having a molecular weight 400 orless and at least one oligomer of n²=0 in the aforementioned generalformula (2) and having a molecular weight of 400 or less.

Both aspects of the production method of granular epoxy resin provides agranular epoxy resin which exhibits excellent fluidity during moldingbecause of its low melt viscosity and yet allows easy handling becauseit hardly causes blocking during storage and transportation.

A package of a granular epoxy resin of the present invention has anenvelope-like container containing therein the granular epoxy resin ofthe present invention. The envelope-like container is made of asynthetic resin film having a water vapor permeability rate of 50g/m²·day or less at 40° C. with 90% relative humidity.

The package of a granular epoxy resin prevents the moisture absorptionof the granular epoxy resin during storage and transportation, therebypreventing the blocking.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The granular epoxy resin according to the present invention is solid atordinary temperature and is mainly composed of at least one selectedfrom oligomers represented by the aforementioned general formula (1) andoligomers represented by the aforementioned general formula (2). In oneembodiment, the epoxy resin includes components having a molecularweight of 500 or less among components of which number of repeats orcycles is 0 occupy 50% by mass or more of the entire epoxy resin. Inanother embodiment, the epoxy resin includes components having amolecular weight of 400 or less among components of which number ofrepeats or cycles is 0 occupy 20% by mass or more of the entire epoxyresin.

Among solid-type epoxy resins to be used as granular epoxy resin of thepresent invention, examples of resin which is mainly composed ofoligomer(s) represented by the aforementioned formula (1) include epoxyresins which are derived from polyhydric phenol compounds such as phenolnovolak resin, cresol novolak resin, bisphenol-A novolac resin, phenolaralkyl resin, biphenyl phenol resin, terpene phenol resin, anddicyclopentadiene phenol resin, with epihalohydrin. Examples of thepolyhydric phenol compounds include polyhydric phenol resins obtained bycondensation reaction of phenol and aldehyde such as benzaldehyde orhydroxy benzaldehyde.

Examples of solid epoxy resin which is mainly composed of oligomer(s)represented by the aforementioned formula (2) include epoxy resins whichare derived from bisphenols with epihalohydrin. Examples of bisphenolsinclude bisphenol A, bisphenol F, tetramethyl bisphenol F, bisphenol AD,bisphenol AP, biphenol, tetramethyl biphenol, dihydroxy diphenyl ether,thiodiphenols, and dihydroxy stilbenes.

The solid epoxy resin according to the present invention may be composedof a single one of these epoxy resins or two or more of these epoxyresins.

Each of the epoxy resins is solid in amorphous or crystalline state atordinary temperature. Concretely, from the viewpoint of handling, theepoxy resins are required to have a softening point of 45° C. or more,preferably 50° C. or more in case of amorphous state and to have amelting point of 30° C. or more, preferably 35° C. or more in case ofcrystalline state. The ordinary temperature used herein means atemperature in a range 5° C. above and below 25° C.

Among the aforementioned resins, the solid epoxy resin to be used forthe granular epoxy resin of the present invention is a resin in whichcomponents having a molecular weight of 500 or less among components ofn¹=0 in the aforementioned general formula (1) and components of n²=0 inthe aforementioned general formula (2) occupy 50% by mass or more of theentire epoxy resin, or, components having a molecular weight of 400 orless among the components of n¹=0 and the components n²=0 occupy 20% bymass or more of the entire epoxy resin.

The resin itself hardly causes blocking, when the molecular weights ofthe components of n¹=0 and the components of n²=0 are large, the contentof components having a molecular weight of 500 or less among thecomponents of n¹=0 and components having a molecular weight of 500 orless among the components of n²=0 is a predetermined amount or less, orthe content of components having a molecular weight of 400 or less amongthe components of n¹=0 and components having a molecular weight of 400or less among the components of n²=0 is a predetermined amount or less.In this case, therefore, the reduction in content of compounds having amolecular weight of 200 or less according to the present inventioncannot be effective.

According to the granular epoxy resin of the present invention, in anepoxy resin which easily causes blocking because the content ofcomponents having low molecular weight among components of which numberof polymerization degree is 0 exceeds a predetermined amount, thecontent of compounds having a molecular weight of 200 or less(hereinafter, referred to as “low molecular weight compound”) is 0.3% bymass or less.

Examples of the low molecular weight compounds in the epoxy resininclude water, residuals of organic compounds used during a process ofproducing epoxy resin, for example, methyl isobutyl ketone, toluene andxylene used as a reaction solvent. The smaller the content of these lowmolecular weight compounds in the epoxy resin is, the higher the effectof preventing the blocking exhibits. Particularly, the content of thelow molecular weight compounds is preferably 0.25% by mass or less, morepreferably 0.20% by mass or less. However, excessively reducing thecontent of the low molecular weight compounds makes the purifyingprocess described later complex, thus leading increase in cost. When thelower limit of the content of the low molecular weight compounds isabout 0.05% by mass, the enough effect of preventing the blocking can beobtained.

The form of the granular epoxy resin of the present invention is notlimited to spherical and may be a block form, a virgulate form, a plateform, or another form. The finer the particles of the epoxy resin are,the easier the blocking is caused. In this case, therefore, thereduction in content of compounds having a molecular weight of 200 orless according to the present invention can be very effective. That is,in case of a powder or granular epoxy resin which contains particleshaving a maximum particle diameter of 30 mm or less, particularly 20 mmor less, in an amount of 80% by mass or more, the effect of preventingthe blocking of the present invention can exhibit well. The maximumparticle diameter used herein means the length of the longest portion ofparticle of the epoxy resin.

The method of producing the granular epoxy resin of the presentinvention is not particularly specified. However, the production methodof granular epoxy resin according to the present invention is preferablebecause the granular epoxy resin can be produced easily andinexpensively.

In the production method of the granular epoxy resin according to thepresent invention, as the first step, the polyhydric phenol resin and/orthe bisphenol react with epihalohydrin in the presence of alkali metalhydroxide so that they are converted into glycidyl ethers. This reactionmay be conducted in a known manner.

Used as the epihalohydrin for this reaction is generally epichlorohydrinor epibromohydrin. Used as the alkali metal hydroxide is generally NaOHor KOH.

The molecular weights and the content of the components of n¹=0 in theaforementioned general formula (1) and the components of n²=0 in theaforementioned general formula (2) are adjusted according to the kind(s)of the selected phenol(s) as their material and the reaction conditionwith the epihalohydrin.

There are many treatment methods after reaction, but normally, saltsproduced as a by-product and excessive alkali metal hydroxide areremoved from the produced epoxy resin solution by washing with water.

As the used solvent for the reaction, excessive epihlorohydrin may bedirectly used or an organic solvent which is not active relative to theother reaction may be used. Examples of the organic solvent includemethyl ethyl ketone, methyl isobutyl ketone, toluene, and xylene.

As the next step of the production method of granular epoxy resinaccording to the present invention, the thus obtained epoxy resinsolution is treated by removing low molecular weight compounds such asthe solvent, the reaction water, or the water entering during thewashing, thus obtaining an epoxy resin in which the content of lowmolecular weight compounds is small.

The method of removing low molecular weight compounds is not specified.However, the method by distillation is preferable because the removal oflow molecular weight compounds can be achieved easily and inexpensively.Examples of the removing method by distillation include a batchdistillation using a distillation still and a continuous distillationusing a rotary evaporator.

This purifying process is conducted to satisfy a condition that thetotal content of low molecular weight compounds having a molecularweight of 200 or less in the epoxy resin becomes 0.28% by mass or less,preferably 0.25% by mass or less, more preferably 0.20% by mass or less.

The actual distillation condition depends on the aspect of the epoxyresin and the boiling point of the low molecular weight compounds to beremoved. In case of the batch distillation, usually, the temperature isfrom 50° C. to 230° C., the residence time is from 30 minutes to 5hours, and the pressure is from 0.5 Torr to 100 Torr. In case of thecontinuous distillation, usually, the temperature is from 50° C. to 230°C., the residence time is from 0.5 minutes to 10 minutes, and thepressure is from 0.5 Torr to atmospheric pressure.

Since the epoxy resin just after removing the low molecular weightcompounds is normally in a molten state, the epoxy resin is cooled andthus converted into solid in amorphous or crystalline state and is thengranulated. The granulation may be conducted simultaneously with thesolidification by using a drop former or conducted by solidifying andaggregating the epoxy resin and then pulverizing the aggregated epoxyresin by using a mill such as a hummer mill, a ball mill, a feathermill, a pulverizer, or a jet mill. The granulated solid epoxy resin isaccommodated in an envelope-like container for storage ortransportation.

In the processes of solidification, granulation, packaging, and storageafter the purifying process, various conditions must be satisfied insuch a manner that the content of low molecular weight compounds havinga molecular weight of 200 or less in the granular epoxy resin neverexceed 0.3% by mass. For example, it must be careful not to allow theentry of low molecular weight compounds having a molecular weight of 200or less from various equipments and the atmosphere. In particular, sincethe epoxy resin is generally hygroscopic, it is required not to absorbmoisture in the atmosphere. As an example of the method for this, thehumidity and the like in the atmosphere are adjusted by an airconditioner and the solidification and the like are conducted in asealed system.

Since the epoxy resin tends to absorb moisture also during storage ortransportation, the container used for packing the granular epoxy resinof the present invention is preferably made of a material having lowmoisture permeability. The material having low moisture permeability maybe a synthetic resin film which is made of polyolefin, polyamide,polyester, polystyrene, or polyvinylchloride and has a water vaporpermeability rate of 50 g/m²·day or less at 40° C. with 90% relativehumidity, more preferably a composite film which has an aluminum layerand/or a silicon oxide layer on a surface of such a synthetic resin filmor between layers of such a synthetic resin film and has a water vaporpermeability rate of 5 g/m²·day or less at 40° C. with 90% relativehumidity. The above-mentioned synthetic resin film may be a laminatedfilm comprising films made of two or more different materials. In theabove-mentioned composite film, the aluminum layer or the silicon oxidelayer may be prepared as a membrane and laminated on the synthetic resinfilm or may be directly formed on the synthetic resin film by vapordeposition.

The preferable packaging form of the granular epoxy resin of the presentinvention is a granular epoxy resin package obtained by accommodatingthe granular epoxy resin of the present invention into an envelope-likecontainer which is made by forming the synthetic resin film having awater vapor permeability rate of 50 g/m²·day at 40° C. with 90% relativehumidity or the composite film having a water vapor permeability rate of5 g/m²·day at 40° C. with 90% relative humidity into an envelope-likeconfiguration. The method of forming the envelope-like container is notparticularly specified. However, it is required to seal joint portion(s)by heat seal or the like so as not to spoil the moisture proofness. Itis preferable to also seal the mouth by heat seal or the like afterfilled with the granular epoxy resin. The content of the granular epoxyresin package is in a range of 0.5–50 kg, preferably 1.0–30 kg in termsof handling property and the like. Though the container may be made ofthe synthetic resin film only, a paper layer may be provided as anexterior or the granular epoxy resin package may be put into a paperenvelope in order to prevent the photo-aging of the granular epoxy resinand prevent the slippage when stacked.

Since the granular epoxy resin of the present invention can exhibitexcellent fluidity during molding because of its low melt viscosity andallows easy handling because it hardly causes blocking during storageand transportation, the granular epoxy resin can be used for various useapplications. According to the production method of granular epoxy resinof the present invention, the granular epoxy resin of the presentinvention having the aforementioned advantages can be easily produced.The granular epoxy resin package of the present invention can preventthe blocking of the granular epoxy resin of the present invention due tomoisture during the storage or transportation.

Hereinafter, examples of the granular epoxy resins of the presentinvention and comparative examples will be given.

In every example, the content of components of n¹=o or n²=0 in resin wasmeasured according to the GPC analysis using an RI detector. Organiccompounds having moisture weight of 200 or less were measured by gaschromatography analysis. The water content was measured by Karl Fishertiltration method.

EXAMPLE 1

775 g of a polycondensation of phenol and benzaldehyde [a phenolcompound which was represented by the aforementioned general formula (1)where G was a hydrogen atom, X was a benzylidene group, p¹ was 0, and n¹was an integer between 0 and 5 and in which the content of components ofwhich n¹ was 0 was 43% by mass] and 2775 g of epichlorohydrin were fedinto a three-neck flask of which capacity was 5 liter and which wasprovided with a temperature indicator, an agitator, and a cooling pipe,and were heated to a temperature of 90° C. so that they were molten.After that, 412.5 g of sodium hydroxide aquous solution of 48.5% by masswas delivered by drops into the solution, taking one hour. During this,the temperature of the reaction liquid was maintained at 95° C. orhigher so as to cause azeotoropy of the reaction liquid. Condensateliquid was obtained by cooling vapor evaporating from the reactionliquid. The obtained condensate liquid was subjected to the oillayer/water layer separation. The oil layer was returned back to thereaction system after removing the water layer. In this manner, thereaction system was dehydrated. The dehydration was continued for 30minutes even after the dropping of the sodium hydroxide solution. Then,excessive epichlorohydrin was distilled from the thus obtained productunder reduced pressure, thereby obtaining a crude epoxy resin.

The crude epoxy resin was solved in 1250 g of methyl isobutyl ketone(MIBK). 10 g of sodium hydroxide aquous solution of 48.5% by mass wasadded into the solution and was maintained at a temperature of 70° C. toreact for one hour. After the reaction, sodium dihydrogen phosphate wasadded to neutralize the excessive sodium hydroxide. Salts produced as aby-product were removed by washing with water. Then, the methyl isobutylketone and water were distilled by heating under reduced pressure.Finally, the thus obtained product was subjected to distillationtreatment at a pressure of 10 Torr and at a temperature of 150° C. for30 minutes, thereby obtaining an epoxy resin in the molten state.

The epoxy resin can be represented by the general formula (1) where Xwas a benzylidene group, p¹ was 0, and n¹ was an integer between 0 and 5and in which the content of components of n¹=0 (having a molecularweight of 388) was 36% by mass and, at this point, the content of methylisobutyl ketone was 0.05% by mass and water content was 0.01% by mass orless. No compound of which molecular weight was 200 or less was detectedbesides the methyl isobutyl ketone and water (the content of lowmolecular weight compounds in the epoxy resin was 0.06% by mass).

The epoxy resin in the molten state was placed in a sealed container andwas then gradually cooled to solidify the epoxy resin. After that, thesolidified resin was pulverized by a hammer mill in the atmosphere at atemperature of 20° C. and a relative humidity of 50% in such a manner asto obtain a granular epoxy resin in which particles having a maximumparticle diameter of 2 mm or less occupy 90% by mass.

The epoxy resin was an umber solid having an epoxy equivalent of 225g/eq., a softening point of 63° C., and a melt viscosity of 0.11 Pa·s at150° C. and in which, at this point, the content of methyl isobutylketone was 0.05% by mass and water content was 0.05% by mass (thecontent of low molecular weight compounds in the granular epoxy resinwas 0.1% by mass).

A composite film [water vapor permeability rate (40° C. with 90%relative humidity): 0.5 g/m²·day] was prepared by laminating a nylonfilm (15 microns) and an LLDPE film (70 microns) which was treated withantistatic finish onto a gas barrier film available from MitsubishiPlastics, Inc. trademark: TECHBARRIER V [silica-vacuum-coatedpolyethylene terephthalate film (12 microns)]. An envelope which was 20cm in width×30 cm in height was made of the composite film byheat-sealing three sides other than the top. The envelope was filledwith 1 kg of granular epoxy resin produced as mentioned above and wassealed by heat sealing. The envelope was inserted into a paper baghaving three layers of Kraft paper, thus completing a granular epoxyresin package.

The granular epoxy resin package was stored under ambient conditions ata temperature of 25° C. and a relative humidity of 85% and the resininside the package was checked for the change with time in low molecularweight compound content (water and MIBK) and the blocking state of theresin was observed. The results are shown in Table 1.

COMPARATIVE EXAMPLE 1

After the reaction between the phenol compound and the epichlorohydrin,washing with water, and the like in the same manner as Example. 1,methyl isobutyl ketone and water were distilled by heating under reducedpressure. Finally, the thus obtained product was subjected todistillation treatment at a pressure of 50 Torr and at a temperature of150° C. for 30 minutes, thereby obtaining an epoxy resin. At this point,the content of methyl isobutyl ketone was 0.5% by mass and water contentwas 0.02% by mass (the content of low molecular weight compounds in theepoxy resin was 0.52% by mass).

After that, he epoxy resin was solidified, pulverized, and packaged inthe same manner as Example 1, thereby producing a granular epoxy resinpackage. At a point just after the packaging, the content of methylisobutyl ketone in the granular epoxy resin was 0.52% by mass and watercontent in the granular epoxy resin was 0.07% by mass (the content oflow molecular weight compounds in the granular epoxy resin was 0.59% bymass).

The granular epoxy resin package was stored under ambient conditions ata temperature of 25° C. and a relative humidity of 85% and the resininside the package was checked for the change with time in low molecularweight compound content (water and MIBK) and the blocking state of theresin was observed. The results are shown in Table 1.

COMPARATIVE EXAMPLE 2

A granular epoxy resin was produced in the same manner as Example 1except that the solidification was conducted in an open container underambient conditions at a temperature of 25° C. and a relative humidity of85% and the pulverization was conducted also in the same ambientconditions. Also, a granular epoxy resin package was made in the samemanner as Example 1. At a point just after the packaging, the content ofmethyl isobutyl ketone in the granular epoxy resin was 0.05% by mass andwater content in the granular epoxy resin was 0.32% by mass (the contentof low molecular weight compounds in the granular epoxy resin was 0.37%by mass).

The granular epoxy resin package was stored under ambient conditions ata temperature of 25° C. and a relative humidity of 85% and the resininside the package was checked for the change with time in low molecularweight compound content (water and MIBK) and the blocking state of theresin was observed. The results are shown in Table 1.

REFERENCE EXAMPLE 1

A paper bag having three layers of Kraft paper (water vapor permeabilityrate (40° C. with 90% relative humidity): 100 g/m²·day or more) wasfilled with 1 kg of a granular epoxy resin manufactured in the samemanner as Example 1 and was sealed with glue, thereby making a granularepoxy resin package.

The granular epoxy resin package was stored under ambient conditions ata temperature of 25° C. and a relative humidity of 85% and the resininside the package was checked for the change with time in low molecularweight compound content (water and MIBK) and the blocking state of theresin was observed. The results are shown in Table 1.

COMPARATIVE EXAMPLE 3

A granular epoxy resin was produced in the same manner as ComparativeExample 1 except using 800 g of a polycondensation product of phenol andbenzoic aldehyde in which the content of components of n¹=0 was 21% bymass. Also, a granular epoxy resin package was made in the same manneras Comparative Example 1.

The epoxy resin was an umber solid in which the content of components(having a molecular weight of 388) of n¹=0 was 17% by mass and having anepoxy equivalent of 231 g/eq., a softening point of 76° C., and a meltviscosity of 0.57 Pa·s at 150° C. At a point just after the packaging,the content of methyl isobutyl ketone in the granular epoxy resin was0.65% by mass and water content in the granular epoxy resin was 0.08% bymass (the content of low molecular weight compounds in the granularepoxy resin was 0.73% by mass).

The granular epoxy resin package was stored under ambient conditions ata temperature of 25° C. and a relative humidity of 85% and the resininside the package was checked for the change with time in low molecularweight compound content (water and MIBK) and the blocking state of theresin was observed. The results are shown in Table 1.

EXAMPLE 2

A granular epoxy resin was produced in the same manner as Example 1except using 605 g of 2,6-xylenol dimer instead of the polycondensationproduct of phenol and benzoic aldehyde. Also, a granular epoxy resinpackage was made in the same manner as Example 1.

The epoxy resin can be represented by the aforementioned general formula(2) where Y was a direct bond, R² was a methyl group, p² was 2, and n²was an integer between 0 and 3 and in which the content of components(having a molecular weight of 354) of n²=0 was 86% by mass and was afaintly-yellow solid having an epoxy equivalent of 185 g/eq., a meltingpoint of 106° C., and a melt viscosity of 0.02 Pa·s at 150° C. At apoint just after the packaging, the content of methyl isobutyl ketone inthe granular epoxy resin was 0.04% by mass and water content in thegranular epoxy resin was 0.03% by mass (the content of low molecularweight compounds in the granular epoxy resin was 0.07% by mass).

The granular epoxy resin package was stored under ambient conditions ata temperature of 25° C. and a relative humidity of 85% and the resininside the package was checked for the change with time in low molecularweight compound content (water and MIBK) and the blocking state of theresin was observed. The results are shown in Table 1.

EXAMPLE 3

A granular epoxy resin was produced in the same manner as Example 1except using 392 g of a polycondensation product of phenol and hydroxybenzoic aldehyde [a phenol compound which was represented by theaforementioned general formula (1) where G was a hydrogen atom, X was agroup represented by the general formula (3), p¹ was 0, R³ was ahydrogen atom, and n¹ was an integer between 0 and 4 and in which thecontent of components of which n¹ was 0 was 52% by mass] and 93 g of4,4′-bisphenol instead of the polycondensation product of phenol andbenzoic aldehyde. Also, a granular epoxy resin package was made in thesame manner as Example 1.

The epoxy resin was a mixture of about 80% by mass of an epoxy resinwhich was represented by the aforementioned general formula (1) where Xwas a group represented by the general formula (3), p¹ was 0, R³ was ahydrogen atom, and n¹ was an integer between 0 and 4 and about 20% bymass of an epoxy resin which was represented by the aforementionedgeneral formula (2) where Y was a direct bond, p² was 0, and n² was aninteger between 0 and 3 and in which the content of components (having amolecular weight of 460) of n¹=0 was 37% by mass and the content ofcomponents (having a molecular weight of 298) of n²=0 was 18% by mass.The epoxy resin was a faintly-yellow solid having an epoxy equivalent of163 g/eq. and a melt viscosity of 0.04 Pa·s at 150° C. At a point justafter the packaging, the content of methyl isobutyl ketone in thegranular epoxy resin was 0.04% by mass and water content in the granularepoxy resin was 0.04% by mass (the content of low molecular weightcompounds in the granular epoxy resin was 0.08% by mass)

The granular epoxy resin package was stored under ambient conditions ata temperature of 25° C. and a relative humidity of 85% and the resininside the package was checked for the change with time in low molecularweight compound content (water and MIBK) and the blocking state of theresin was observed. The results are shown in Table 1.

TABLE 1 Comparative Comparative Reference Comparative Example 1 Example2 Example 3 Example 1 Example 2 Example 1 Example 3 N = 0 componentMolecular weight of 55 500 or less (% by mass) Molecular weight of 36 8618 36 36 36 17 400 or less (% by mass) Melt viscosity at 150° C. 0.110.02 0.04 0.11 0.11 0.11 0.57 (Pa · s) Just after packaging Watercontent 0.05 0.03 0.04 0.07 0.32 0.05 0.08 (% by mass) MIBK content 0.050.04 0.04 0.52 0.05 0.05 0.65 (% by mass) 10 days after Water content0.05 0.03 0.04 0.07 0.32 0.21 0.08 (% by mass) MIBK content 0.05 0.040.04 0.52 0.05 0.05 0.64 (% by mass) Blocking State ∘ ∘ ∘ Δ Δ ∘ ∘ 20days after Water content 0.06 0.03 0.05 0.08 0.33 0.30 0.08 (% by mass)MIBK content 0.05 0.04 0.04 0.52 0.05 0.05 0.63 (% by mass) BlockingState ∘ ∘ ∘ x x Δ ∘ 30 days after Water content 0.07 0.04 0.07 0.08 0.350.48 0.09 (% by mass) MIBK content 0.05 0.04 0.04 0.51 0.05 0.04 0.63 (%by mass) Blocking State ∘ ∘ ∘ x x x ∘ Note for Table 1 Blocking state ∘:Granular state equivalent to that just after packaging Δ: Blockingpartially occurs x: Blocking entirely occurs

As apparent from Table 1, the granular epoxy resin of the presentinvention can exhibit excellent fluidity during molding because of itslow melt viscosity and yet allows easy handling because it hardly causesblocking during storage and transportation. As described in Examples,the production method of granular epoxy resin of the present inventionallows easy production of the epoxy resin of the present invention.

1. A granular epoxy resin as a granular matter of an epoxy resin whichis solid at ordinary temperature and is mainly composed of at least oneselected from oligomers represented by the following general formula (1)and oligomers represented by the following general formula (2), whereinat least 50% by mass of the entire epoxy resin consists of at least oneoligomer of n¹=0 in the following general formula (1) and having amolecular weight of 500 or less and/or at least one oligomer of n²=0 inthe following general formula (2) and having a molecular weight of 500or less; and the total content of compounds having a molecular weight of200 or less is 0.3% by mass or less of the entire epoxy resin;

wherein in formula (1) hereinabove, G is a glycidyl group; R¹ is ahydrocarbon group having from 1 to 10 carbon atoms and each R¹ can bethe same or different; X is a divalent hydrocarbon group having from 1to 18 carbon atoms, —O—, —S—, or a group represented by the followinggeneral formula (3) and each X can be the same or different;

wherein G is a glycidyl group; is a hydrogen atom or a hydrocarbon grouphaving from 1 to 5 carbon atoms; p¹ is an integer between 0 and 4 andeach p¹ can be the same or different; n¹ is an integer between 0 and 10;

wherein in formula (2) hereinabove, R² is a hydrocarbon group havingfrom 1 to 10 carbon atoms and each R² can be the same or different; Y isa divalent hydrocarbon group having from 1 to 18 carbon atoms, —O—, —S—,—CO—, —SO₂—, or a direct bond and each Y can be the same or different;p² is an integer between 0 and 4 and each p² can be the same ordifferent; n² is an integer between 0 and
 10. 2. A granular epoxy resinas a granular matter of an epoxy resin which is solid at ordinarytemperature and is mainly composed of at least one selected fromoligomers represented by the following general formula (1) and oligomersrepresented by the following general formula (2) wherein at least 20% bymass of the entire epoxy resin consists of at least one oligomer of n¹=0in the following general formula (1) and having a molecular weight 400or less and/or at least one oligomer of n²=0 in the following generalformula (2) and having a molecular weight of 400 or less, and the totalcontent of compounds having a molecular weight of 200 or less is 0.3% bymass or less of the entire epoxy resin;

wherein in formula (1) hereinabove, G is a glycidyl group; R¹ is ahydrocarbon group having from 1 to 10 carbon atoms and each R¹ can bethe same or different; X is a divalent hydrocarbon group having from 1to 18 carbon atoms, —O—, —S—, or a group represented by the followinggeneral formula (3) and each X can be the same or different;

(in the above formula (3), G is a glycidyl group, R³ is a hydrogen atomor a hydrocarbon group having from 1 to 5 carbon atoms; p¹ is an integerbetween 0 and 4 and each p¹ can be the same or different; n¹ is aninteger between 0 and 10;

wherein in formula (2) hereinabove, R² is a hydrocarbon group havingfrom 1 to 10 carbon atoms and R² can be the same or different; Y is adivalent hydrocarbon group having from 1 to 18 carbon atoms, —O—, —S—,—CO—, —SO₂—, or a direct bond and each Y can be the same or different;p² is an integer between 0 and 4 and each p² can be the same ordifferent; n² is an integer between 0 and
 10. 3. A granular epoxy resinas claimed in claim 1, wherein the content of particles having a maximumdiameter of 30 mm or less is 80% by mass or more.
 4. A packagecomprising an envelope-like container and a granular epoxy resincontained therein, wherein the granular epoxy resin is as claimed inclaim 1, and said envelope-like container is made of a synthetic resinfilm having a water vapor permeability rate of 50 g/m² day or less at40° C. with 90% relative humidity.
 5. A package as claimed in claim 4,wherein said envelope-like container is made of a composite filmcomprising a synthetic resin film and an aluminum layer and/or a siliconoxide layer having a water vapor permeability rate of 50 g/m² day orless at 40° C. with 90% relative humidity.
 6. A package as claimed inclaim 5, wherein the water vapor permeability rate at 40° C. with 90%relative humidity is 5 g/m² day or less.